【Medical Case Report】 Walking on a Pebble: Morton’s Neuroma Misdiagnosed as Plantar Plate Tear

This case highlights how a patient with persistent forefoot pain, described as “walking on a pebble,” was initially diagnosed with a plantar plate tear based on MRI. Careful clinical examination, however, revealed that the true source of pain was interdigital nerve entrapment — Morton’s neuroma. This report underscores the importance of correlating imaging findings with physical examination to identify the real pain generator.

Patient Information:

She is 67 years old, a nurse, and European.
An adult patient presenting with forefoot pain for approximately 7–8 months.

History of Presenting Illness (HPI):
The patient reported sharp pain localized to the ball of the foot, aggravated by walking barefoot or standing on tiptoes. Pain was especially pronounced when pressure was applied to the forefoot, preventing normal weight-bearing. Symptoms worsened with tight or high-heeled shoes and improved with rest or shoe removal. The patient described the sensation as “walking on a small stone or pebble,” even when barefoot. When standing, the toes appeared spread apart and misaligned.

Previous Consultations and Investigations:

• Initially consulted a podiatrist after noticing pain and abnormal toe alignment.

• X-ray: No fracture identified.

• Referred to a foot specialist.

• MRI findings: Partial plantar plate tear with degenerative changes of the metatarsophalangeal joint.

• Treatment plan from the specialist: follow-up in November; surgery may be considered if the tear does not heal or if symptoms persist.

Physical Examination:

• Marked tenderness between the 3rd and 4th metatarsal heads.

• Mulder’s sign positive.

• Decreased sensation noted over the plantar forefoot, while digital tip sensation remained intact.

Clinical Impression:

• Morton’s neuroma (3rd–4th intermetatarsal space).

• Partial plantar plate tear with degenerative changes (MRI).

Analysis and Reasoning:
Although MRI demonstrated a partial plantar plate tear, the patient’s pain characteristics (stone-in-the-shoe sensation, sharp neuralgic pain, Mulder’s sign positivity, forefoot sensory changes) strongly suggest interdigital nerve entrapment as the primary pain generator.
It is possible that the plantar plate tear represents an older injury or background pathology, contributing to toe misalignment and predisposing the interdigital nerve to compression. However, the true source of the patient’s pain is more consistent with nerve entrapment rather than the tear itself.

Conclusion:
Yes, the tear may be an old injury and not the direct source of pain; the real symptoms come from nerve entrapment. This distinction highlights the importance of separating imaging findings from the clinical presentation, which reflects the true value of careful clinical examination.

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